A solid-state infrared spectrometer using the acousto-optic tunable filter (AOTF) coupled to fluoride glass fibers will be developed to monitor airway gases such as carbon dioxide, nitrous oxide, and the anesthesia agents. This system can rapidly access multiple wavelengths to identify the various anesthesia agents and determine the concentration of the gases. Fiber optic coupling allows the measurement to be performed using a small flow cell attached directly to the airway tubing. The advantages of using the AOTF include small size, high speed, and no moving parts. The spectrometer will be optimized for the 3 4.5 micron range where the gases absorb. The fluoride fiber will also be optimized for better transmission at 4.3 microns.